[Determinants of quality of life in patients with somatoform disorders with pain as main symptom - the case for differentiating subgroups].

Objectives: What impact do the degree of somatization and the presence of a comorbid psychological disorder have on health-related quality of life in patients with pain-dominated somatoform disorders?

Methods: 282 consecutive patients (57.6 %) from a total population of N=490 patients fulfilling the criteria of somatoform pain disorders were included in the study following a thorough interdisciplinary diagnostic process at a German university hospital. Structured interviews (SKIDI and SKID-II) to assess comorbid psychological disorders as well as a structured biographical interview to assess chronification factors were conducted. We employed the Screening for Somatoform Disorders form (SOMS) to discover the extent and distribution of somatic symptoms and the SF-36 to determine the health-related quality of life.

Results: The patients exhibited a multiplicity of further somatic complaints apart from pain. 69 % had a comorbid psychological disorder. The health-related physical and psychological quality of life was clearly impaired in patients with "small", "substantial" and "pronounced" somatization. Regression analysis explained 48 % of the variance of the body-related and 35 % of the variance of the psychological quality of life: Besides the extent of somatization, older age, duration of pain-associated hospitalizations and the subjective amount of occupational impairment proved to be important. With regard to the psychological (but not the somatic) health-related quality of life, the presence of a current comorbid psychological disorder was also relevant.

Conclusion: Patients with pain-dominated somatoform disorders are substantially impaired in their quality of life. Because 31 % of the patients with such disorders have no additional comorbid psychic disorder and the existence of a comorbid psychic disorder impacts only the psychological domain of their health-related quality of life, the results appear to strongly support maintaining the diagnostic category of somatoform disorders in ICD-11 and DSM-V. They also support the grading of the severity of the somatization similar to the grading of depressive disorders.